Events Archive

Nov
25
2014
Mathematical Models of the Ebola Virus Disease Outbreak in West Africa: Principles, Predictions, and Control
The Ebola epidemic in West Africa has spurred an international response. This response has been strongly influenced by epidemiological models that predicted a devastating rise in cases without large-scale changes in behavior and intervention. In this talk, I introduce the mathematical principles underlying predictions of the rate and scope of a disease epidemic. I then explain how such principles have been applied to forecasting Ebola virus disease (EVD) dynamics and identifying the type and scale of necessary control. One control mechanism involves influencing behavior and social norms to limit post-death transmission, e.g., during burial ceremonies of...
Nov
24
2014
Molecular Biomechanics and Mechanobiology
The cell can be thought of as an organized collection of molecular machines. As such, many biomolecules can have moving parts, generate, bear and leverage forces, and convert chemical energy to mechanical work and vice versa. In this talk I will use several examples to illustrate how mechanics can regulate biology at the molecular scale.  
Nov
19
2014
Vitrification as Compared to Gelation in Amorphous Polymers
Gelation and vitrification are the most common mechanisms for a liquid-to-solid transition in amorphous materials. For both, a heterogeneous, percolating internal structure grows and reduces the mobility of internal constituents. Macroscopic rheological properties are strongly affected but appear to be very similar for gelation and vitrification. Here we propose a novel rheological test to distinguish between gelation and vitrification. The test is based on Boltzmann’s equation of linear viscoelasticity and focuses on the distribution of relaxation modes in samples near the liquid-to-...
Nov
18
2014
Distant Horizons: New Worlds in an Age of Discovery
Great voyages of exploration have always been driven in large part by an insatiable curiosity to know what is beyond the furthest horizon you can see. Five hundred years ago, the European exploration of the globe was a central feature of the expanding scientific and artistic explosion we call the Renaissance and Enlightenment. Today, we are once again witnessing an age of exploration and discovery, as we push beyond the shores of Earth, looking deep into the far reaches of space. You and I live in an age where, for the first time in...
Nov
18
2014
Polymers in strong flows: shear banding, fracture, and other strange phenomena
Entangled polymers have been thoroughly studied since the 1940s at least....or so we thought. In the last decade particle velocimetry and other imaging methods, combined with rheology, have shown that some dramatic instabilities can occur in strongly sheared well-entangled polymer melts. I will discuss how some of these new observations (such as various shear banding phenomena and `fracture') can be understood in terms of the 'Standard Model' for entangled polymers, and highlight some of the current controversies in the area.
Nov
12
2014
How to become a better cook by bringing science to the kitchen
In this talk we will bring parallels of science and cooking to the fore.  Using a wide variety of kitchen cooking techniques whose inner workings on the molecular level can be explained through chemistry and physics we hope to make the science and the food more easily understandable.  We will cover topics ranging from surface tension, diffusion processes, gelation, crystallization and viscoelasticity. The overall...
Nov
11
2014
Computational studies of virus assembly around nucleic acids and on lipid membranes
For many viruses, the spontaneous assembly of a capsid shell around the nucleic acid (NA) genome is an essential step in the viral life cycle. Understanding how this process depends on the charge, structure, and sequence of the nucleic acid could promote biomedical efforts to block viral propagation and guide the reengi-neering of capsids for gene therapy applications. This talk will describe coarse-grained models of capsid proteins and NAs which enable dynamical simulations of...
Nov
10
2014
The science behind animal-inspired robotics
The 21st Century has seen an explosion of bio-inspired technology and devices. Perhaps no where has this approach been more transformative than in the field of mobile robotics. Geckos, snakes, and even cockroaches have motivated new sticky, stable, steerable robots. Yet inspiration means more than curiosity. As scientists we must unravel the scientific principles and mechanisms underlying animal performance. By studying the physics of these living systems we can inform a systematic approach to animal-inspired robotics. By doing so, we discover new properties and dynamics of complex systems -- the robots themselves even...
Nov
10
2014
Ion Motion in Gases, A Colloquium in Honor of Dr. Ian Gatland
The history of drift-tube measurements of gaseous ion transport coefficients is reviewed, with an emphases on the contributions made by Dr. Gatland.  The use of experimental measurements of such coefficients in testing ion-neutral interaction potentials over wide ranges of internuclear separation is illustrated through recent tests of ab initio potentials.  Finally, the use of such data with recent theoretical advances is shown to have implications for ion-neutral reactions of importance in the ionosphere. ...
Nov
07
2014
Quantum Oscillations in Kondo Insulator SmB6
In Kondo insulator samarium hexaboride SmB6, strong correlation and band hybridization lead to a diverging resistance at low temperature. The resistance divergence ends at about 3 Kelvin, a behavior recently demonstrated to arise from the surface conductance. However, questions remain whether and where a topological surface state exists. Quantum oscillations have not been observed to map the Fermi surface. We solve the problem by resolving the Landau Level quantization and Fermi surface topology using torque magnetometry. The observed angular dependence of the Fermi surface cross section suggests two-dimensional surface...

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